To hold the reference, insert $ as such:

$C$4

A quick way to do this is click on the cell reference in
your formula and continually press F4 until you arrive at
the type of reference you want.

HTH
Jason
Atlanta, GA

-----Original Message-----
hi there,
I need to enter the following formula into series of
cells;

=DEGREES(ATAN((C4-C18)/(B4-B18)))

I need to copy the formula into a range of cells, but
keeping 'C4' and 'B4'
in the formula. 'C18' and 'B18' are variable to the
range of selected cells.
When selecting the range of cells and 'filling down'
with the formula. C4 and
B4 change to C5 B5, C6 B6, C7 B7, etc etc.

I know i could just enter the values of C4 and B4 within
the formula, but
these may change peridically. It would be easier to
change the values on the
worksheet rather than within any formulas i had.

Hope all this makes sense, Any help would be appreciated
.